The immediate goal of this research is to provide a deeper understanding of the similarities and differences between the biological properties of v-src, the transforming gene of Rous sarcoma virus (RSV), and its normal homologue, c-src. Ultimately, the hope is to obtain insight into the molecular mechanisms of src-induced transformation. A rat cell line, 2A-2, that expresses an exogenously added chicken c-src gene will be used to analyze the properties of pp60[unreadable]c-src[unreadable]. Additionally, cell lines containing higher levels of rp60[unreadable]c-src[unreadable] will be made. This will be done by cloning c-src into efficient expression vectors and adding the chimeric molecules to cells as part of a calcium-phosphate precipitate. Among the properties of pp60[unreadable]c-src[unreadable] that are of interest are its: half-life, sites of phosphorlation, protein kinase activity, and interactions with other cellular proteins. Not only will pp60[unreadable]c-src[unreadable] be studied, but also chimeric genes that are part c-src and part v-src. These genes will provide insight into the differences that enable one gene (v-src) to transform cells (and cause tumors) while the other cannot. Cell lines will also be created that contain mutant v-src genes. These cell lines will provide further insight into the life cycle of pp60[unreadable]src[unreadable] if they contain proteins with identifiable behavioral changes (e.g., inability to bind to a membrane or lack of phosphorylation). The cell lines will also be the targets for mutagenesis experiments. These experiments are designed to alter cellular constitutents that interact with pp60[unreadable]src[unreadable]. An appropriate mutation will complement the deficiency in pp60[unreadable]src[unreadable] and restore the wild-type transforming behavior. Such genes that interact with pp60[unreadable]src[unreadable] will be isolated for further study. Finally, a retrovirus vector will be made that will be used to identify promoters turned on or off in a scr-transformed cell. This vector will allow for the selection of cells containing promoters that signal a beginning or an and to transcription after src-mediated transformation. Those promoters (and accordingly the genes with which they are associated) will be isolated for further study. (X)